SDL: Introduction to cells

Question 1

What is the cell membrane

Answer 1

Plasma membrane, barrier allowing transport of molecules between extracellular environment and interior of cells, organelles also bound by plasma membrane

Question 2

What is the basic structure of the cell membrane?

Answer 2

• Lipid bilayer, mainly composed of lipids, with proteins and associated carbohydrates throughout
• Bilipid structure due to phospholipids having hydrophilic head, hydrophobic tail - sometimes referred to as fluid mosaic model
• Individual phospholipids can move, forming dynamic structure in which:
• Lateral movement of molecules aids cell mobility
• Membrane semipermeable
• Breaks and tears sealed quickly
• Larger molecules such as proteins can become embedded

Question 3

What are the 4 types of phospholipid?

Answer 3

• Phosphatidyl serine
• Phosphatidyl inositol
• Phosphatidyl choline
• Phosphatidyl ethanolamine

Question 4

What is the function of cholesterol in the cell membrane?

Answer 4

Acts to limit the movement of the phospholipids, making the membrane more rigid, therefore extent of fluidity highly dependent on cholesterol

Question 5

What is the function of glycolipids in the cell membrane?

Answer 5

• May be involved in intracellular communication

Question 6

Describe the types of proteins that can be found in the cell membrane

Answer 6

• Structural proteins - Protein that attach cytoskeletal filaments to cell membrane, adhesion molecules which attach cells to extracellular matrix
• Transport proteins such as carrier, pump, and channel proteins
• Proteins with enzymatic activity
• Proteins can be embedded in membrane or associated with membrane surface